The N- and O-linked carbohydrate chains of human, bovine and porcine plasminogen. Species specificity in relation to sialylation and fucosylation patterns

Abstract

The structures of the N-and O-glycans of human, bovine and porcine plasminogen were determined by 500-MHz 1H-NMR spectroscopy. The N-glycans of all three species proved to be of the N-acetyllactosamine type differing from one another with respect to the sialylation and fucosylation patterns. In the N-glycan of human plasminogen the two antennae are sialylated with N-acetylneuraminic acid (NeuAc), whereas in the bovine counterpart both branches carry significant amounts of N-glycolylneuraminic acid (NeuGc). In porcine plasminogen the sialic acid is mainly NeuAc; the Manalpha1->6 branch, however, is only partially sialylated. In addition, the porcine N-glycan is fucosylated to about 80% in alpha1->6 linkage to the GlcNAc-1 residue. The O-glycans of the three species possess an identical Galbeta1->3GalNAc core which is alpha2->3 sialylated with NeuAc at Gal. The disialylated form, which is also present in all three species, has an additional NeuAc residue in alpha2->6 linkage to GalNAc. Mono-and disialylated forms occur in different molar ratios in the different plasminogens: 80:20 in human, 70:30 in bovine and 50:50 in porcine. This study on the carbohydrate moiety of these three plasminogens reveals species specificity in terms of various types of microheterogeneities.